Spindle motor

ABSTRACT

A spindle motor is provided, the motor including: a base plate; a PCB Printed Circuit Board arranged on an upper surface of the base plate; a bearing assembly coupled to the base plate; a stator coupled to a periphery of the bearing assembly; and a rotor rotationally coupled to the bearing assembly, wherein the base plate is formed with a foreign object inflow prevention fence to inhibit inflow of foreign objects into the stator and the base plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119 of KoreanApplication No. 10-2010-0115160, filed Nov. 18, 2010, which is herebyincorporated by reference in its entirety.

BACKGROUND

The present disclosure generally relates to a spindle motor.

A spindle motor performs a function of rotating a disk to enable anoptical pickup which linearly reciprocates in an optical disk drive ODDand a hard disk to read a large amount of data recorded on the disk. TheODDs have been recently developed to stably rotate an optical disk at ahigh speed.

The ODD includes a spindle motor for rotating an optical disk at a highspeed, an optical pickup module for reading out data from a diskrotating at a high speed or recording the data on the disk, and astepping motor for driving the optical pickup module.

The spindle motor rotating the optical disk at a high speed includes abearing rotationally supporting a rotation shaft, a bearing housingaccommodating the bearing, a stator secured at a periphery of thebearing housing, a rotor rotationally accommodated on the bearing, abase plate fixing the bearing housing and a circuit substrate arrangedat an upper surface of the base plate.

A gap is formed between an upper surface of the base plate and thestator according to a conventional spindle motor to disadvantageouslyintroduce foreign objects. In order to reduce the gap formed between thestator and the upper surface of the base plate, the circuit substratearranged on the upper surface of the base plate is unnecessarilyextended to a bottom surface of the stator. If the circuit substrate isextended to between the stator and the base plate, inflow of foreignobjects into the base plate and the stator may be reduced to a certaindegree. However, a problem occurs in which an area of the high-pricedcircuit substrate disadvantageously increases to increase amanufacturing cost of the spindle motor.

BRIEF SUMMARY

Exemplary embodiments of the present disclosure provide a spindle motorconfigured to reduce a manufacturing cost by dispensing with unnecessaryextension of a circuit substrate into between a stator and a base plateand by preventing foreign objects from entering the stator and the baseplate.

In one general aspect of the present disclosure, there is provided aspindle motor, the spindle motor comprising: a base plate; a PCB PrintedCircuit Board arranged on an upper surface of the base plate; a bearingassembly coupled to the base plate; a stator coupled to a periphery ofthe bearing assembly; and a rotor rotationally coupled to the bearingassembly, wherein the base plate is formed with a foreign object inflowprevention fence to prevent inflow of foreign objects into the statorand the base plate.

Preferably, a part of the PCB opposite to the stator is removed toexpose part of the base plate.

Preferably, the PCB is formed with an exposure unit exposing a part ofthe base plate opposite to the stator, and the foreign object inflowprevention fence inhibits foreign objects from entering through theexposure unit.

Preferably, the base plate is formed with a first through hole to becoupled to the bearing assembly, and the PCB is formed with a secondthrough hole formed at a position corresponding to that of the firstthrough hole and partially opened by the exposure unit.

Preferably, each corner of the PCB opposite to the stator is formed at aposition corresponding to that of each distal end of the foreign objectinflow prevention fence.

Preferably, the foreign object inflow prevention fence takes a shape ofa curved line when viewed in a top plane.

Preferably, the foreign object inflow prevention fence has the samecurvature as that of a core of the stator.

Preferably, a height of the foreign object inflow prevention fence issubstantially same as thickness of the PCB.

Preferably, the foreign object inflow prevention fence is erected at aright angle relative to the base plate.

Preferably, the height of the foreign object inflow prevention fence ishigher than the thickness of the PCB.

Preferably, the foreign object inflow prevention fence is erected at anobtuse angle relative to the base plate.

Preferably, the foreign object inflow prevention fence is erected at anacute angle relative to the base plate.

Preferably, the foreign object inflow prevention fence is formed bybending a part of the base plate.

Preferably, the foreign object inflow prevention fence is formed by asynthetic resin coated on the base plate in the shape of a strip.

Preferably, the synthetic resin includes an elastic member havingelasticity.

Preferably, the base plate includes a semi-circular lug when viewed in atop plane.

Preferably, the foreign object inflow prevention fence is manufacturedwith synthetic resin, and the foreign object inflow prevention fenceincluding the synthetic resin is attached to the base plate by adhesive.

Preferably, the spindle motor further includes a foreign objectattachment member arranged at a rear surface of the foreign objectinflow prevention fence to which foreign objects introduced into theforeign object inflow prevention fence are attached.

Preferably, the foreign object attachment member includes an adhesivematerial to which foreign objects having passed the foreign objectinflow prevention fence are attached.

Preferably, the bearing assembly includes a bearing housing and abearing inserted into the bearing housing, and the stator includes acore having radially formed core pieces and a coil wound on the corepieces, and the rotor includes a magnet opposite to the core pieces anda yoke fixing the magnet and coupled to the rotation shaft inserted intothe bearing.

In another general aspect of the present disclosure, there is provided aspindle motor, the spindle motor comprising: a base plate; a PCB PrintedCircuit Board arranged on an upper surface of the base plate; a bearingassembly coupled to the base plate; a stator coupled to a periphery ofthe bearing assembly, a part of which is protruded from an edge of thebase plate; and a rotor rotationally coupled to the bearing assembly,wherein the base plate is formed with a lug covering a bottom surface ofthe stator protruded from the edge of the base plate, and the lug isformed with a foreign object inflow prevention fence to inhibit inflowof foreign objects into the stator and the base plate.

Preferably, the stator includes a plurality of core units radiallyformed to be wound with a coil, and the lug takes a shape of asemi-circular plate along a distal end of the radially formed coreunits.

Preferably, the edge of the lug takes a shape of a curvature when viewedin a top plane.

Preferably, a void space is formed at a portion corresponding to the lugto reduce an area of the PCB.

Preferably, the foreign object inflow prevention fence takes a shape ofa curved plate along the edge of the lug.

Preferably, an inner surface of the foreign object inflow preventionfence is formed at a position corresponding to a distal end of thestator.

Preferably, the PCB is formed with a through hole through which thebearing assembly passes, and a diameter of the through hole is largerthan that of the bearing assembly.

Preferably, the through hole is partially opened.

Preferably, a height of the foreign object inflow prevention fencemeasured from an upper surface of the base plate is substantially sameas that of the PCB arranged on an upper surface of the base plate.

Preferably, the foreign object inflow prevention fence is formed bybending an edge of the lug of the base plate toward the stator.

Preferably, the foreign object inflow prevention fence is formed by asynthetic resin coated in the shape of a strip along the edge of the lugof the base plate.

Preferably, the foreign object inflow prevention fence is formed by asynthetic resin coated on the base plate in the shape of a strip.

Preferably, the rotor includes a rotation shaft rotationally coupled tothe bearing assembly, a yoke coupled to the rotation shaft and partiallyarranged opposite to a distal end of the stator, and a magnet arrangedat the yoke opposite to the distal end of the stator, wherein theforeign object inflow prevention fence is arranged at an inner lateralsurface of the yoke.

Preferably, the spindle motor further includes a foreign objectattachment member formed on an upper surface of the lug of the baseplate and having viscosity for attracting foreign objects introducedinto the foreign object inflow prevention fence.

Preferably, the foreign object attachment member includes a syntheticresin having viscosity or a double-sided adhesive tape.

Preferably, both distal ends of the foreign object inflow preventionfence are brought into contact with the PCB.

In still another general aspect of the present disclosure, there isprovided a spindle motor, the spindle motor comprising: a base plateformed with a first through hole; a PCB arrange at an upper surface ofthe base plate and having a second through hole corresponding to thefirst through hole; a bearing assembly coupled to the first through holeof the base plate; a stator coupled to a periphery of the bearingassembly and including a core, a part of which is protruded from an edgeof the base plate, and a coil wound on the core; and a rotor including arotation shaft rotationally coupled to the bearing assembly, a yokecoupled to the rotation shaft and a magnet coupled to the yoke and beingopposite to the core, wherein the base plate is formed with a lugcovering a bottom surface of the core partially protruded from the edgeof the base plate, and an edge of the lug is formed with a foreignobject inflow prevention fence bent from the edge of the lug toward thecore to prevent inflow of foreign objects to the core and the baseplate.

Preferably, the foreign object inflow prevention fence takes asemi-circular shape along a periphery of the core.

Preferably, a height of the foreign object inflow prevention fencemeasured from an upper surface of the base plate is substantially sameas thickness of the PCB.

Preferably, the spindle motor further includes a foreign objectattachment member formed on an upper surface of the lug of the baseplate and having viscosity for attracting foreign objects introducedinto the foreign object inflow prevention fence.

Preferably, the foreign object inflow prevention fence is formed by asynthetic resin coated or hardened in the shape of a strip along anupper surface of the edge of the lug.

The spindle motor according to the exemplary embodiments of the presentdisclosure has an advantageous effect in that an exposure unit is formedat a part of a PCB interposed between a base plate and a core of astator to reduce a manufacturing cost of the PCB, and foreign objectsintroduced through the exposure unit is inhibited by a foreign objectinflow prevention fence formed at the base plate to avoid the spindlemotor from being polluted by the foreign objects.

Additional advantages, objects, and features of the disclosure will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thedisclosure. The objectives and other advantages of the disclosure may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Accompanying drawings are included to provide a further understanding ofarrangements and embodiments of the present disclosure and areincorporated in and constitute a part of this application. In thefollowing drawings, like reference numerals refer to like elements andwherein:

FIG. 1 is a perspective view of a spindle motor according to anexemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional view taken along line 1-1′ of FIG. 1;

FIG. 3 is a plane view illustrating a spindle motor of FIG. 1 removed ofa rotation shaft and a rotor;

FIG. 4 is a partially enlarged perspective view illustrating a spindlemotor of FIG. 3 removed of a stator; and

FIG. 5 is a lateral view of FIG. 1.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure aredescribed in detail with reference to the accompanying drawings. In thedrawings, sizes or shapes of constituent elements may be exaggerated forclarity and convenience.

Particular terms may be defined to describe the disclosure in the bestmode as known by the inventors. Accordingly, the meaning of specificterms or words used in the specification and the claims should not belimited to the literal or commonly employed sense, but should beconstrued in accordance with the spirit and scope of the disclosure. Thedefinitions of these terms therefore may be determined based on thecontents throughout the specification. The meaning will be clear fromthe context of the description. Like numbers refer to like elementsthroughout, and explanations that duplicate one another will be omitted.

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. Such an industry-accepted tolerance rangesfrom less than one percent to ten percent and corresponds to, but is notlimited to, component values, angles, et cetera.

Any reference in this specification to “one embodiment,” “anembodiment,” “exemplary embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the disclosure. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to affect such feature, structure, orcharacteristic in connection with others of the embodiments.

FIG. 1 is a perspective view of a spindle motor according to anexemplary embodiment of the present disclosure, FIG. 2 is across-sectional view taken along line 1-1′ of FIG. 1, FIG. 3 is a planeview illustrating a spindle motor of FIG. 1 removed of a rotation shaftand a rotor, FIG. 4 is a partially enlarged perspective viewillustrating a spindle motor of FIG. 3 removed of a stator, and FIG. 5is a lateral view of FIG. 1.

Referring to FIGS. 1 to 5, a spindle motor 800 includes a bearingassembly 100, a stator 200, a rotation shaft 300, a rotor 400, a baseplate 500 and a PCB Printed Circuit Board, 700. In addition, the spindlemotor 800 may further include a clamp 600.

The bearing assembly 100 includes a bearing housing 110 and a bearing120. The bearing housing 110 takes a shape of a hollow hole-formedcylinder, for example, and the bearing housing 110 is formed at an uppercorner with a staircase sill 115 for securing a core described later.The bearing housing 110 is protruded at a rear surface with a couplinglug 117 for being coupled with the base plate 500, described later.

The bearing housing 110 is arranged at a bottom surface with a supportplate 119 for supporting a bottom end of the rotation shaft 300,described later, and a portion contacting a bottom end of the rotationshaft 300 in the support plate 119 is formed with a thrust bearing 119a.

The bearing 120 takes a shape of a cylinder inserted into the bearinghousing 110, and is formed with a rotation shaft hole for being coupledwith the rotation shaft. In the exemplary embodiment of the presentdisclosure, the bearing 120 may include an oil sintered impregnationbearing.

The stator 200 includes a core 210 and a coil 220. The core 210 isformed by stacking a plurality of iron pieces each having an opening,and secured to the staircase sill 115 of the bearing housing 100. In theexemplary embodiment of the present disclosure, the core 210 includescore units 212, where the core units 212 are formed by being radiallyprotruded, and the core 210 including the core units 212 takes a shapeof a disk when viewed in a top plane.

In the exemplary embodiment of the present disclosure, a part of thecore 210 including the core units 212 may be arranged to protrude froman edge of the base plate 500. The coil 220 is wound on the core unit212 formed at the core 210.

The rotation shaft 300 is inserted into the rotation shaft hole of thebearing 120 at the bearing assembly 100, and a bottom end of therotation shaft 300 is brought into contact with the thrust bearing 119 asupported by the support plate 119.

The rotor 400 includes a yoke 410 and a magnet 420. In addition, therotor 400 may further include a suction magnet 430. The yoke 410 mayinclude a yoke upper plate 412 and a yoke lateral plate 414.

The yoke upper plate 412, when viewed from a top plane, takes a shape ofa disk, and is centrally formed with a cylindrically shaped yoke burringunit 413 towards an upper surface of the yoke upper plate 412. The yokeburring unit 413 is press-fitted into the rotation shaft 300.

The yoke lateral plate 414 is downwardly extended from the yoke upperplate 412 and a void is formed inside the yoke 410 by the yoke lateralplate 414 and the yoke upper plate 412.

The magnet 420 is formed along an inner lateral surface of the yokelateral plate 414, and a rotational force is generated on the yoke 410and the rotation shaft 300 by attractive force and repulsive forcegenerated a magnetic field generated by the coil 220 wound on the coreunit 212 of the core 210 and a magnetic field generated by the magnet420. The yoke upper plate 412 of the yoke 410 is arranged with a clamp600 for chucking an optical disk.

Meantime, a suction magnet 430 may be arranged at any one place of aninner lateral surface of the yoke upper plate 412 and an upper surfaceof the core 210 opposite to the inner lateral surface of the yoke upperplate 412.

In the exemplary embodiment of the present disclosure, the suctionmagnet 430 may be arranged at the inner lateral surface of the yokeupper plate 412, for example, and the suction magnet 430 arranged at theinner lateral surface pulls the core 210 using the magnetic force tostably rotate the rotor 400.

Referring to FIGS. 2, 3 and 4 again, the base plate 500 is formed byprocessing a metal plate. The base plate 500 is formed with a throughhole 502 corresponding to the hollow hole of the bearing housing 110 atthe bearing assembly 100, as shown in FIG. 2.

The base plate 500 is formed with a lug 510 formed in a shapecorresponding to the core 210 of the stator 200, and the lug 510 maytake a semi-disk semi-circular shape when viewed in a top plane. Thus,foreign objects can be initially inhibited by the lug 510 from enteringan interior of the spindle motor through a bottom surface of the core210.

The PCB 700 is arranged at an upper surface of the base plate 500, andis mounted with a variety of circuit elements, where the PCB 700 iselectrically connected to the coil 220 which is a constituent element ofthe stator 200. The PCB 700 is formed with a through hole 505 forpreventing an interference with the bearing housing 110. Size of thethrough hole 505 formed at the PCB 700 is larger than that of a throughhole 502 formed at the base plate 505. The through hole 505 of the PCB700 is partially opened and the opened portion of the through hole 505may be formed with a curvature.

Referring to FIGS. 2 and 5, a bottom surface of the core 210 coupled tothe bearing housing 110 of the bearing assembly 100 coupled to the baseplate 500 is discrete from an upper surface of the base plate 500 at apredetermined gap, where various foreign objects such as dust, fineparticles, oily dust and the like can be introduced into the base plate500 and the bottom surface of the core 210, and the foreign objects canbe attached to the core 210, the coil 220, the bearing and the magnet420, and life of the spindle motor 800 can be greatly reduced by theforeign objects attached thereto.

In order to inhibit the foreign objects from introducing into the gapbetween the upper surface of the base plate 500 and the bottom surfaceof the core 210, a partial area of the PCB 700 may be extended to bearranged on the lug 510 of the base plate 500.

In a case the PCB 700 covers the semi-disk lug 510 of the base plate500, the gap between the upper surface of the base plate 500 and thebottom surface of the core 210 is reduced as much as thickness of thePCB 700 to decrease inflow of the foreign objects.

However, in a case the high-priced PCB 700 is unnecessarily extended tocover the lug 510 of the base plate 500, a manufacturing cost of thespindle motor 800 is inevitably increased.

In the exemplary embodiment of the present disclosure, the PCB 700 isformed with an exposure unit 710 that exposes the semi-disk lug 510 ofthe base plate 500 as illustrated in FIG. 4. The closed through hole 505formed at the PCB 700 is opened by the exposure unit 710.

In the exemplary embodiment of the present disclosure, the frequentlyused “exposure unit” is defined by a portion exposing the base plate 500that is formed by removing a part corresponding to a part opposite tothe core 210 in the PCB 700 arranged on the base plate 500.

A portion corresponding to the semi-disk lug 510 is formed the byexposure unit with a void space not formed with the PCB 700. In a casethe exposure unit 710 exposing a part of the semi-disk shaped lug 510 ofthe base plate opposite to the core 210 is formed on the PCB 700, anarea of the PCB 700 is reduced whereby a manufacturing cost of the PCB700 can be decreased but the foreign objects can be introduced in thespindle motor through the exposure unit 710.

In the exemplary embodiment of the present disclosure, in order toinhibit the foreign objects from entering through the exposure unit 710of the PCB 700 formed between the upper surface of the base plate 500and the bottom surface of the core of the stator 200, a foreign objectinflow prevention fence 520 is formed at the base plate 500.

The foreign object inflow prevention fence 520 is formed along an edgeof the semi-disk shaped lug 510 and takes a shape of curved fence. Adistal end of the curvature-shaped foreign object inflow preventionfence 520 is brought into contact with a distal end of the PCB 700formed by the exposure unit 710, and the other distal end correspondingto the distal end of the foreign object inflow prevention fence 520 isbrought into contact with the other distal end corresponding to thedistal end of the PCB 700 formed by the exposure unit 710.

In the exemplary embodiment of the present disclosure, a height of theforeign object inflow prevention fence 520 may be substantially same asthickness of the PCB, for example. Alternatively, it should be apparentthat the height of the foreign object inflow prevention fence 520 isgreater than the thickness of the PCB.

The foreign object inflow prevention fence 520 may be erected at a rightangle relative to the base plate 500. Alternatively, the foreign objectinflow prevention fence 520 may be erected at an obtuse angle or anacute angle relative to the base plate 500. In the exemplary embodimentof the present disclosure, the foreign object inflow prevention fence520 may be formed by bending an edge of the semi-circular lug 510 of thebase plate 500 to a direction facing the core 210. In the exemplaryembodiment of the present disclosure, the foreign object inflowprevention fence 520 formed by bending the edge of the semi-circular lug510 of the base plate 500 is formed in the shape of a curved plate.

Although a gap between the base plate 500 and the bottom surface of thecore 210 of the stator 200 may increase by the PCB 700 formed with theexposure unit 710 for reducing the manufacturing cost, the foreignobjects can be blocked by the foreign object inflow prevention fence 520formed at the base plate 500 through the formation of the foreign objectinflow prevention fence 520 formed at the base plate 500.

In the exemplary embodiment of the present disclosure, both distal endsof the foreign object inflow prevention fence 520 are brought intocontact with the PCB 700, whereby inflow of foreign objects areinhibited from entering a space formed between the distal end of theforeign object inflow prevention fence 520 and the PCB 700.

Although the exemplary embodiments of the present disclosure haveillustrated and explained a structure in which a part of the base plate500 is bent to form the foreign object inflow prevention fence 520, itshould be apparent that the foreign object inflow prevention fence isalternatively formed by a synthetic resin material hardened along anupper edge of the lug 510 of the base plate 500 in a strip shape andcoated on the base plate 500 using a dispenser. At this time, it shouldbe apparent that the synthetic resin material has elasticity free fromgenerating a static electricity, such that even if the synthetic resinmaterial is brought into contact with the rotating yoke 410, no noiseand damage can be generated.

Meanwhile, in order to inhibit foreign objects such as dust introducedthrough the foreign object inflow prevention fence 520 from attaching toessential parts of the spindle motor despite the formation of theforeign object inflow prevention fence 520, a foreign object attachmentmember may be arranged at a rear surface of the foreign object inflowprevention fence to which foreign objects introduced into the foreignobject inflow prevention fence are attached. The foreign objectattachment member may include an adhesive material having viscosity towhich foreign objects having passed the foreign object inflow preventionfence 520 are attached.

Meanwhile, the foreign object inflow prevention fence 520 preventinginflow of foreign objects may be manufactured with a synthetic resinmaterial, and the foreign object inflow prevention fence 520manufactured with the synthetic resin material may be attached to thebase plate by an adhesive.

As apparent from the foregoing, the spindle motor according to theexemplary embodiments of the present disclosure has an industrialapplicability in that an exposure unit is formed at a part of a PCBinterposed between a base plate and a core of a stator to reduce amanufacturing cost of the PCB, and foreign objects introduced throughthe exposure unit is prevented by a foreign object inflow preventionfence formed at the base plate to avoid the spindle motor from beingpolluted by the foreign objects.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis invention. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A spindle motor, the spindle motor comprising: abase plate; a PCB Printed Circuit Board arranged on an upper surface ofthe base plate; a bearing assembly coupled to the base plate; a statorcoupled to a periphery of the bearing assembly; and a rotor rotationallycoupled to the bearing assembly, wherein the base plate is formed with aforeign object inflow prevention fence to inhibit inflow of foreignobjects into the stator and the base plate.
 2. The spindle motor ofclaim 1, wherein a part of the PCB opposite to the stator is removed toexpose part of the base plate.
 3. The spindle motor of claim 1, whereinthe PCB is formed with an exposure unit exposing a part of the baseplate opposite to the stator, and the foreign object inflow preventionfence inhibits foreign objects from entering through the exposure unit.4. The spindle motor of claim 1, wherein the base plate is formed with afirst through hole to be coupled to the bearing assembly, and the PCB isformed with a second through hole formed at a position corresponding tothat of the first through hole and partially opened by the exposureunit.
 5. The spindle motor of claim 1, wherein each corner of the PCBopposite to the stator is formed at a position corresponding to that ofeach distal end of the foreign object inflow prevention fence.
 6. Thespindle motor of claim 1, wherein the foreign object inflow preventionfence takes a shape of a curved line when viewed in a top plane.
 7. Thespindle motor of claim 6, wherein the foreign object inflow preventionfence has the same curvature as that of a core of the stator.
 8. Thespindle motor of claim 1, wherein a height of the foreign object inflowprevention fence is substantially same as thickness of the PCB.
 9. Thespindle motor of claim 1, wherein the foreign object inflow preventionfence is erected at a right angle relative to the base plate.
 10. Thespindle motor of claim 1, wherein the height of the foreign objectinflow prevention fence is higher than the thickness of the PCB.
 11. Thespindle motor of claim 1, wherein the foreign object inflow preventionfence is erected at an obtuse angle relative to the base plate.
 12. Thespindle motor of claim 1, wherein the foreign object inflow preventionfence is erected at an acute angle relative to the base plate.
 13. Thespindle motor of claim 1, wherein the foreign object inflow preventionfence is formed by bending a part of the base plate.
 14. The spindlemotor of claim 1, wherein the foreign object inflow prevention fence isformed by a synthetic resin coated on the base plate in the shape of astrip.
 15. The spindle motor of claim 14, wherein the synthetic resinincludes an elastic member having elasticity.
 16. The spindle motor ofclaim 1, wherein the base plate includes a semi-circular lug when viewedin a top plane.
 17. The spindle motor of claim 1, wherein the foreignobject inflow prevention fence is manufactured with synthetic resin, andthe foreign object inflow prevention fence including the synthetic resinis attached to the base plate by adhesive.
 18. The spindle motor ofclaim 1, further comprising: a foreign object attachment member arrangedat a rear surface of the foreign object inflow prevention fence to whichforeign objects introduced into the foreign object inflow preventionfence are attached.
 19. The spindle motor of claim 18, wherein theforeign object attachment member includes an adhesive material to whichforeign objects having passed the foreign object inflow prevention fenceare attached.
 20. The spindle motor of claim 1, wherein the bearingassembly includes a bearing housing and a bearing inserted into thebearing housing, and the stator includes a core having radially formedcore pieces and a coil wound on the core pieces, and the rotor includesa magnet opposite to the core pieces and a yoke fixing the magnet andcoupled to the rotation shaft inserted into the bearing.
 21. The spindlemotor of claim 1, further comprising: a foreign object attachment memberformed on an upper surface of the lug of the base plate and havingviscosity for attracting foreign objects introduced into the foreignobject inflow prevention fence.
 22. A spindle motor, the spindle motorcomprising: a base plate; a PCB Printed Circuit Board arranged on anupper surface of the base plate; a bearing assembly coupled to the baseplate; a stator coupled to a periphery of the bearing assembly, a partof which is protruded from an edge of the base plate; and a rotorrotationally coupled to the bearing assembly, wherein the base plate isformed with a lug covering a bottom surface of the stator protruded fromthe edge of the base plate, and the lug is formed with a foreign objectinflow prevention fence to inhibit inflow of foreign objects into thestator and the base plate.
 23. The spindle motor of claim 22, whereinthe stator includes a plurality of core units radially formed to bewound with a coil, and the lug takes a shape of a semi-circular platealong a distal end of the radially formed core units.
 24. The spindlemotor of claim 23, wherein the edge of the lug takes a shape of acurvature when viewed in a top plane.
 25. The spindle motor of claim 22,wherein a void space is formed at a portion corresponding to the lug toreduce an area of the PCB.
 26. The spindle motor of claim 22, whereinthe foreign object inflow prevention fence takes a shape of a curvedplate along the edge of the lug.
 27. The spindle motor of claim 26,wherein an inner surface of the foreign object inflow prevention fenceis formed at a position corresponding to a distal end of the stator. 28.The spindle motor of claim 22, wherein the PCB is formed with a throughhole through which the bearing assembly passes, and a diameter of thethrough hole is larger than that of the bearing assembly.
 29. Thespindle motor of claim 28, wherein the through hole is partially opened.30. The spindle motor of claim 22, wherein a height of the foreignobject inflow prevention fence measured from an upper surface of thebase plate is substantially same as that of the PCB arranged on an uppersurface of the base plate.
 31. The spindle motor of claim 22, whereinthe foreign object inflow prevention fence is formed by bending an edgeof the lug of the base plate toward the stator.
 32. The spindle motor ofclaim 22, wherein the foreign object inflow prevention fence is formedby a synthetic resin coated in the shape of a strip along the edge ofthe lug of the base plate.
 33. The spindle motor of claim 22, whereinthe foreign object inflow prevention fence is formed by a syntheticresin coated on the base plate in the shape of a strip.
 34. The spindlemotor of claim 22, wherein the rotor includes a rotation shaftrotationally coupled to the bearing assembly, a yoke coupled to therotation shaft and partially arranged opposite to a distal end of thestator, and a magnet arranged at the yoke opposite to the distal end ofthe stator, wherein the foreign object inflow prevention fence isarranged at an inner lateral surface of the yoke.
 35. The spindle motorof claim 22, further comprising a foreign object attachment memberformed on an upper surface of the lug of the base plate and havingviscosity for attracting foreign objects introduced into the foreignobject inflow prevention fence.
 36. The spindle motor of claim 35,wherein the foreign object attachment member includes a synthetic resinhaving viscosity or a double-sided adhesive tape.
 37. The spindle motorof claim 22, wherein both distal ends of the foreign object inflowprevention fence are brought into contact with the PCB.
 38. A spindlemotor, the spindle motor comprising: a base plate formed with a firstthrough hole; a PCB arrange at an upper surface of the base plate andhaving a second through hole corresponding to the first through hole; abearing assembly coupled to the first through hole of the base plate; astator coupled to a periphery of the bearing assembly and including acore, a part of which is protruded from an edge of the base plate, and acoil wound on the core; and a rotor including a rotation shaftrotationally coupled to the bearing assembly, a yoke coupled to therotation shaft and a magnet coupled to the yoke and being opposite tothe core, wherein the base plate is formed with a lug covering a bottomsurface of the core partially protruded from the edge of the base plate,and an edge of the lug is formed with a foreign object inflow preventionfence bent from the edge of the lug toward the core to inhibit inflow offoreign objects to the core and the base plate.
 39. The spindle motor ofclaim 38, wherein the foreign object inflow prevention fence takes asemi-circular shape along a periphery of the core.
 40. The spindle motorof claim 38, wherein a height of the foreign object inflow preventionfence measured from an upper surface of the base plate is substantiallysame as thickness of the PCB.
 41. The spindle motor of claim 38, whereinthe foreign object inflow prevention fence is formed by a syntheticresin coated or hardened in the shape of a strip along an upper surfaceof the edge of the lug.